Cell signalling

Cell Signalling is the transfer of information, that controls the cell behaviour, whether from cell to cell, or from environment to cell.
There are many different types of cell signalling that vary immensley. About 10-15% of the genome codes for the creation of these cell signalling molecules. Most signals involved are chemicals but some can be physical signals such as light.

Different signalling mecahnisms are used depending on how far the signal needs to travel. For short distances, there is a pathway between adjacent cells and takes place via a gap junction. The pathway size then increase from gap junction, to contact dependant, where the signal is displayed on the surface and a receptor on another cell surface, for example, an immune response cell. Paracrine pathways secrete a signal into the interstitial fluid within the same tissue. The next longer pathway is Autocrine signalling and Synaptic signalling. The longest signalling pathway, which usually has the longest response time to the stimulus is Endocrine signalling, where the signal is secreted into the blood stream which flows around the body.

There are 5 stages; Signal, Reception, Transduction, Amplification and Response